fix: correctly send links to login v2 in email notifications (#10711)

# Which Problems Are Solved

There were still some emails (passkey registration and domain claimed)
sent with links pointing to login v1 even when the login v2 was enabled
for the instance.
Also while looking into the issue, it was discovered that some links
pointing to login V2 were not correctly generated.


# How the Problems Are Solved

- Added default paths for passkey registration and domain claimed
notifications
- Fixed the existing paths to properly handle concatenation (resp. use
`url.ResolveReference`)
  - Change their go types (from string) to `*url.URL` 
  - Added a mapstructure hook for string to url
- Removed unnecessary `InstanceSetupFeatures` and corresponding
conversions
- Refactored the methods on the `login.DefaultPaths` struct and added an
interface to the `Commands` to only need to pass a single config (and
not every method)
- Added an `OriginURL` method to the `DomainCtx` to prevent going from
url to string and back
- Added the use of the templates in case of enabled login v2 for passkey
registration and domain claimed)

# Additional Changes

None

# Additional Context

closes #10643

---------

Co-authored-by: Max Peintner <[email protected]>
Co-authored-by: Livio Spring <[email protected]>
Co-authored-by: Livio Spring <[email protected]>
Co-authored-by: Max Peintner <[email protected]>
Co-authored-by: Gayathri Vijayan <[email protected]>

internal/command/command.go

@@ -98,11 +98,18 @@ type Commands struct {
 	caches *Caches
 	// Store instance IDs where all milestones are reached (except InstanceDeleted).
 	// These instance's milestones never need to be invalidated,
-	// so the query and cache overhead can completely eliminated.
+	// so the query and cache overhead can be completely eliminated.
 	milestonesCompleted sync.Map
 
-	defaultEmailCodeURLTemplate   func(ctx context.Context) string
-	defaultPasswordSetURLTemplate func(ctx context.Context) string
+	loginPaths LoginPaths
+}
+
+//go:generate mockgen -package command -destination ./mock_login_paths.go . LoginPaths
+type LoginPaths interface {
+	DefaultEmailCodeURLTemplate(ctx context.Context) string
+	DefaultPasswordSetURLTemplate(ctx context.Context) string
+	DefaultPasskeySetURLTemplate(ctx context.Context) string
+	DefaultDomainClaimedURLTemplate(ctx context.Context) string
 }
 
 func StartCommands(
@@ -120,12 +127,9 @@ func StartCommands(
 	httpClient *http.Client,
 	permissionCheck domain.PermissionCheck,
 	sessionTokenVerifier func(ctx context.Context, sessionToken string, sessionID string, tokenID string) (err error),
-	defaultAccessTokenLifetime,
-	defaultRefreshTokenLifetime,
-	defaultRefreshTokenIdleLifetime time.Duration,
+	defaultAccessTokenLifetime, defaultRefreshTokenLifetime, defaultRefreshTokenIdleLifetime time.Duration,
 	defaultSecretGenerators *SecretGenerators,
-	defaultEmailCodeURLTemplate func(ctx context.Context) string,
-	defaultPasswordSetURLTemplate func(ctx context.Context) string,
+	loginPaths LoginPaths,
 ) (repo *Commands, err error) {
 	if externalDomain == "" {
 		return nil, zerrors.ThrowInvalidArgument(nil, "COMMAND-Df21s", "no external domain specified")
@@ -211,10 +215,9 @@ func StartCommands(
 				WithHyphen: defaults.Multifactors.RecoveryCodes.WithHyphen,
 			},
 		},
-		GenerateDomain:                domain.NewGeneratedInstanceDomain,
-		caches:                        caches,
-		defaultEmailCodeURLTemplate:   defaultEmailCodeURLTemplate,
-		defaultPasswordSetURLTemplate: defaultPasswordSetURLTemplate,
+		GenerateDomain: domain.NewGeneratedInstanceDomain,
+		caches:         caches,
+		loginPaths:     loginPaths,
 	}
 
 	if defaultSecretGenerators != nil && defaultSecretGenerators.ClientSecret != nil {